| Prefabricated flaps are used to transplant well-known blood vessels to random flaps,or to transplant free skin flaps onto tissues containing vascular bundles and rich blood vessels,such as fascia and omentum.The flap actively increases the blood flow of the flap to achieve the purpose of applying the new blood supply system to supply the flap,and provides a new choice for repairing the reconstructed tissue and organ defects.The core problem of prefabricated flap is the reconstruction of blood supply.Therefore,many scholars hope to promote the revascularization of the prefabricated skin flap and improve its survival rate by applying some interventions.In this study,rabbit autologous inactive platelet-rich plasma was injected into rabbit dorsal prefabricated flap at different times to investigate the survival of prefabricated flaps by topical application of inactive platelet-rich plasma,and establishing a theoretical basis for the clinical use of PRP.Purpose:To establish a model of prefabricated flaps on the back of rabbits,and to explore the optimal concentration of microangiography using lead oxide suspension method.To explore the feasibility of inactive platelet-rich plasma to promote angiogenesis of prefabricated flaps and improve the survival area of flaps.And compare the difference of inactive form of PRP injection at different time to promote the survival of prefabricated flaps.Methods:Fifty healthy male New Zealand white rabbits were used as the research object.A model of a prefabricated flap pedicled with a rabbit thoracodorsal vascular bundle was established by two-stage surgery.Two rabbit flap models were constructed first,and a small piece of flap tissue was taken for HE staining at 7th and 14th day after the first stage of surgery respectively.The second operation time was determined by this results.According to the perfusion concentration of lead oxide,18 rabbits with back prefabricated flaps were divided into 9 groups with 2 in each group,and 9 different concentrations of lead oxide suspension(60%,50%,40%,37%,33%,30%,27%,23%,and 20%)were injected through the aorta respectively.The microangiographic results of gross specimen and local prefabricated flap were observed by X-ray imaging.The prefabricated flaps constructed on both sides of the remaining 30 rabbits were randomly divided into experimental side and control side,with a total of 60 sides.On the experimental side,autologous inactive PRP was injected around the thoracodorsal vascular bundle,and the control side was injected with the same amount of normal saline.According to the preoperative(group A),intraoperative(group B),and postoperative(group C)injections of inactive PRP,30 rabbits were divided into 3 groups,10 in each group.Histological and immunohistochemical observations,vascular density measurement,lead oxide angiography were used to compare the survival rates of prefabricated flaps of three groups of rabbits with different inactive PRP injection time.Results:More microvascular lumens were observed 14 days after the first stage of surgery by HE staining,and the vascularization process was basically mature,at which time the second stage of surgery was feasible.Lead oxide perfusion angiography showed that the tertiary arterial could not be developed at 60%and 50%concentration,and the development was unclear at 40%and 37%,and the development was too weak below 30%.Clear tertiary arterial imaging was obtained at 33%and 30%concentration,and the best contrast was obtained at 33%concentration.Compared with the control side,the survival rate,microvessel density and the expression of VEGF and VEGFR2 in the inactive PRP injection side were significantly increased(p<0.05).The number of VEGFR2-positive cells in the PRP-treated side was increased by 2.48-fold in group A,2.62-fold in group B,and the corresponding VEGF concentration was also significantly increased(p<0.05).Microvessels in group A of PRP-treated side were found by microvascular counts of CD34-positive staining.The density was increased by 4 times,and the B group was significantly increased by 5 times。The appearance of the flap was visually observed 7 days after surgery.The survival rate of the flap in the experimental group B was 97±2%,88±5.5%in the group A,and there was no significant difference between the experimental side of group C and the control group(p>0.05).Conclusion:In this study,a rabbit model of prefabricated flap pedicled with thoracic and dorsal vascular bundles was successfully constructed through two stages of surgery.The angiography method using lead oxide to observe the degree of vascularization of the prefabricated skin flap was cost-effective and convenient,and the microvessels of the skin flap can be clearly displayed at the concentration of 33%.Autologous inactive PRP can promote the survival of the prefabricated flap,and the intraoperative injection can significantly improve the survival rate of the prefabricated flap.It provides a theoretical guidance for obtaining a larger area of prefabricated axial flap in clinical practice. |
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